Of course. They aren't "top-tier" power weapons like the sniper or rockets maybe, but they are power weapons nonetheless. --- One of these days, Valve will confirm Half-Life 3, but nobody will believe them and assume its another ruse.
I would agree with the railgun at least. Perhaps I am not as proficient with it as other weapons, but in my experience it essentially requires actual contact between player and projectile to get kills with; essentially making it a slightly faster, much weaker laser. Have literally landed shots right between people's feet that didn't even deplete their shields with that thing.
Definitely would consider SAW and detonator up there though. I actually tend to choose SAW over launcher weapons nowadays as it's ammo typically lasts longer.